TLS: add an internal function isc__nmhandle_get_selected_alpn()

The added function provides the interface for getting an ALPN tag
negotiated during TLS connection establishment.

The new function can be used by higher level transports.

lib/isc/netmgr/http.c

@@ -1399,8 +1399,7 @@ transport_connect_cb(isc_nmhandle_t *handle, isc_result_t result, void *cbarg) {
 
 		INSIST(transp_sock->type == isc_nm_tlssocket);
 
-		isc_tls_get_selected_alpn(transp_sock->tlsstream.tls, &alpn,
+		isc__nmhandle_get_selected_alpn(handle, &alpn, &alpnlen);
-					  &alpnlen);
 		if (alpn == NULL || alpnlen != NGHTTP2_PROTO_VERSION_ID_LEN ||
 		    memcmp(NGHTTP2_PROTO_VERSION_ID, alpn,
 			   NGHTTP2_PROTO_VERSION_ID_LEN) != 0)

lib/isc/netmgr/netmgr-int.h

@@ -1603,6 +1603,11 @@ void
 isc__nm_tls_failed_read_cb(isc_nmsocket_t *sock, isc_result_t result,
 			   bool async);
 
+void
+isc__nmhandle_tls_get_selected_alpn(isc_nmhandle_t *handle,
+				    const unsigned char **alpn,
+				    unsigned int *alpnlen);
+
 void
 isc__nm_http_stoplistening(isc_nmsocket_t *sock);
 
@@ -2022,3 +2027,15 @@ isc__nmhandle_set_manual_timer(isc_nmhandle_t *handle, const bool manual);
  * Set manual read timer control mode - so that it will not get reset
  * automatically on read nor get started when read is initiated.
  */
+
+void
+isc__nmhandle_get_selected_alpn(isc_nmhandle_t *handle,
+				const unsigned char **alpn,
+				unsigned int *alpnlen);
+/*
+ * Returns a non zero terminated ALPN identifier via 'alpn'. The
+ * length of the identifier is returned via 'alpnlen'. If after the
+ * call either 'alpn == NULL' or 'alpnlen == 0', then identifier was
+ * not negotiated of the underlying protocol of the connection
+ * represented via the given handle does not support ALPN.
+ */

lib/isc/netmgr/netmgr.c

@@ -2922,6 +2922,27 @@ isc__nmhandle_set_manual_timer(isc_nmhandle_t *handle, const bool manual) {
 	UNREACHABLE();
 }
 
+void
+isc__nmhandle_get_selected_alpn(isc_nmhandle_t *handle,
+				const unsigned char **alpn,
+				unsigned int *alpnlen) {
+	isc_nmsocket_t *sock;
+
+	REQUIRE(VALID_NMHANDLE(handle));
+	sock = handle->sock;
+	REQUIRE(VALID_NMSOCK(sock));
+
+	switch (sock->type) {
+#if HAVE_LIBNGHTTP2
+	case isc_nm_tlssocket:
+		isc__nmhandle_tls_get_selected_alpn(handle, alpn, alpnlen);
+		return;
+#endif /* HAVE_LIBNGHTTP2 */
+	default:
+		break;
+	};
+}
+
 #ifdef NETMGR_TRACE
 /*
  * Dump all active sockets in netmgr. We output to stderr

lib/isc/netmgr/tlsstream.c

@@ -1402,3 +1402,18 @@ isc__nmhandle_tls_set_manual_timer(isc_nmhandle_t *handle, const bool manual) {
 
 	sock->manual_read_timer = manual;
 }
+
+void
+isc__nmhandle_tls_get_selected_alpn(isc_nmhandle_t *handle,
+				    const unsigned char **alpn,
+				    unsigned int *alpnlen) {
+	isc_nmsocket_t *sock;
+
+	REQUIRE(VALID_NMHANDLE(handle));
+	sock = handle->sock;
+	REQUIRE(VALID_NMSOCK(sock));
+	REQUIRE(sock->type == isc_nm_tlssocket);
+	REQUIRE(sock->tid == isc_tid());
+
+	isc_tls_get_selected_alpn(sock->tlsstream.tls, alpn, alpnlen);
+}